This invention relates to an adjusting means for the sector plate sealing members of rotary regenerative heat exchangers, and more particularly to an adjusting means which, in response to a thermal deformation of the regenerator body to a dish-like shape of the end surfaces of the regenerator body and the corresponding variation of the sealing spaces, actuates adjusting linkages of the sealing members by means of a servo device so as to maintain a predetermined sealing space, wherein at least one sensing means is attached to each sealing member adjacent a circumferential or annular metal flange or disc supported by the regenerator body.
Adjusting means of this type are known for instance from U.S. Pat. No. 3,232,335 (Canadian Pat. No. 704,958, GB Pat. No. 1,002,235) in which the sensing means are pneumatic, mechanical or magnetic.
One known pneumatic sensing means comprises a nozzle carried by the sealing member, an impingement plate (a circumferential flange) carried by the regenerator body and means for supplying pressure air to the nozzle, the pressure of the air being dependent on the position of said nozzle relative to said impingement plate and the servo device being operable to adjust the position of the sealing member according to that pressure.
Another known mechanical sensing means comprises a sensing lever carried by the sealing member, and a link connecting the lever to a control means for the servo device which is operable to adjust the position of the sealing member in response to displacement of the lever which is adapted to slide on a circumferential flange carried by the regenerator body.
Still another known magnetic sensing means comprises an electro-magnet located to produce a magnetic field between the circumferential flange and a sealing member, the servo device being operable to adjust the position of the sealing member according to current variations due to changes in the strength of the magnetic field, which is dependent on the position of the sealing member relative to the flange.
In all these known arrangements, the inclusion of a servo device brings about the advantage that very large adjustment forces can be produced so that even in very large size heat exchangers readjustment of the sealing members may be effected without difficulties. The smaller forces of the mechanical sensing lever are accompanied only by light wear and for that reason sensing levers of this type have a long working life.
These known arrangements have the disadvantages, however, of being subjected to physical and chemical attacks by the impurities contained in the waste flue gases and to the high temperatures of the gases resulting in a considerable reduction in the life of especially the magnetic sensing means in which the electrical windings or coils and their insulating materials are non-resistant to heat.
The object of this invention is to eliminate or at least reduce the above-mentioned disadvantages.